Kurzfassung englisch

AACHENER INSTITUT FÜR BAUSCHADENSFORSCHUNG
UND ANGEWANDTE BAUPHYSIK GEMEINNÜTZIGE GESELLSCHAFT mbH
PROF. DR.-ING. RAINER OSWALD †
DIPL.-ING. MARTIN OSWALD, M.ENG.
DIPL.-ING. MATTHIAS ZÖLLER
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Durability of connections between liquid sealing materials and damp-proofing sheets, exemplified by accessible and non-accessible flat roofs
Short version
Research project:
Document number: SF - 10.08.18.7-10.28 / II3 - II3-F20-10-63
Funded by: „Forschungsinitiative Zukunft Bau des
Bundesinstitutes für Bau-, Stadt- und Raumforschung“
The responsibility for the contents of the report lies with the authors.
Editor:
AIBAU – Aachener Institut für Bauschadensforschung
und angewandte Bauphysik, gGmbH, Aachen
Project manager:
Prof. Dr.-Ing. Rainer Oswald †
Dipl.-Ing. Matthias Zöller
Others:
Prof. Dr.-Ing. Rainer Oswald †
Dipl.-Ing. Ruth Abel
Dipl.-Ing. Martin Oswald, M.Eng.
Dipl.-Ing. Klaus Wilmes
Dipl.-Ing. Matthias Zöller
In recent years, roofing sheets installed on accessible or non-accessible flat roofs have been more and
more frequently combined with reinforced liquid plastic materials (“Flüssigkunststoffe” - FLK), especially
at the edges and at the joints of above-surface building components. A great number of newly-developed liquid plastics, whose application is comparatively easy, offer economic solutions for the waterproofing of buildings, especially when there are complicated geometric structures with irregular joints.
As the examination of flat roofs and their joints has shown, the connection between liquid waterproofing
materials and roofing sheets has often been prone to failure, though in some cases the damage did not
occur before the end of the usual warranty period of five years. In the present research project, the
practical performance of the connection between waterproofing sheets and liquid plastics has been
assessed by on-site inspections, by the evaluation of expert reports, and by a survey among building
experts and roofers. The survey shows that, as a rule, the connections between sheets and liquid waterproofing materials function adequately. In the cases of defects in the overlapping area, the damage
mostly occurred directly after application works had been finished, in 82 % of the cases within four years
after the completion of works.
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Durability of connections between liquid sealing materials and damp-proofing sheets
Short version
Apart from the degree of sloping in the overlapping area, the position of the connection is an important
criterion for assessment. If the overlap is situated at surface level, it is considered as “lying”; if it is raised
above the water-bearing level, it is termed “standing”.
The requirements for application, which are briefly described below, will ensure the proper function of
the relevant connections:
In standard roof constructions, “lying” connections should reach degree 3 in preliminary tensile tests
(“Schälzugprüfung” according to Swiss Norm SN 564281/2:2011), i.e. a great degree of strength will be
needed to peel off the material by hand; the liquid applied material (FLK) cannot be removed completely.
“Standing” connections should reach degree 4: the liquid materials cannot be removed by hand.
Before application, the underlying surface must be prepared appropriately.
Care must be taken to ensure the required minimum thickness of the liquid applied materials.
It is essential to prevent water from penetrating behind the connections.
Workers need to be trained adequately.
For high quality roofs, “standing” connections should be used to the greatest possible extent. Where
this is not practicable, other constructional techniques have to be used to prevent water from collecting
in the overlapping area.
The required minimum thickness of the liquid plastic materials must be guaranteed by tests and documentation.
The penetration of the roof surface should be minimized as far as possible.
The results of the research project show that the combination of liquid applied materials and dampproofing sheets is a reliable and durable technique, provided that construction and application are in
compliance with the above-mentioned rules. It has been successfully used for several years and should
be incorporated into current building regulations.